Answer:
13,551,737
Step-by-step explanation:
You want the sum of the first 13 terms of the geometric sequence with first term 17, and successive terms 51, 153, ....
Common ratio
The common ratio is found by dividing a sequence term by the one before it:
r = 51/17 = 3
The common ratio is 3.
Index
The index of the 13th term of the sequence is n = 13.
Sum
The sum of n terms of a geometric sequence with first term a1 and common ratio r is ...
Sn = a1·(r^n -1)/(r -1)
For a1 = 17, r = 3, and n = 13, the sum is ...
[tex]S_{13}=17\cdot\dfrac{3^{13}-1}{3-1}=17\cdot\dfrac{1594322}{2}=\boxed{13,\!551,\!737}[/tex]
